Catalytic hydrogenation process



Patented Nov. 24, 1942 CATALYTIC mnocnm'rlos raocsss Frederick E. Frey, Bartlesville, kla., assignor to Phillips 1'! 'rolenm Delaware Company, a corporation of Application November 12, 1938, Serial Ni. 240,195

16 Claims.

Thisinvention relates to catalytic hydrogenation, and particularly to the catalytic, non-destructive hydrogenation of unsaturated carbon to carbon bonds in molecules of organic compounds.

Because oi the exothermic nature of the hydrogenation reaction, much heat is liberated when unsaturated compounds are hydrogenated to saturated compounds. When non-destructive hydrogenation is effected with the aid of a catalyst, control of the temperature of the catalyst is highly important. If the temperature is not controlled properly, portions of a body of catalyst become overheated or underheated; this results in undesired side reactions, such as destructive hydrogenation, in a decreased yield, and often in an increased rate of deactivation and/or deterioration of the catalyst. Overheating of the catalyst is especially detrimental, as it may sinter the active catalytic points and destroy part or, all of the catalytic activity, or otherwise injure the catalyst.

Overheating of the catalyst, for example, may occur because of the development of a localized hot spot or zone in which an overly large fraction of the hydrogenation takes place. The production of such a hot zone is favored when the concentration of the reacting ingredients is high, as at moderate to high superatmospheric pressures, or in the presence of only small amounts of saturated hydrocarbons, for the reaction occurs at a rate that is considerably affected by the concentration of the reactants. In some cases in which the concentration is too high, the heat liberated by the hydrogenation may cause such a cumulative increase in the temperature that the catalyst at that point becomes overheated.

As an overly large fraction of the hydrogenation takes place in the hot zone, other portions of the catalyst do not effect their proper share of the hydrogenation. In other words, the portion of the catalyst within the hot zone carries more than its share of the load and the portions outside of the hot zone carry less than their share. This condition is especially undesirable because the hot zone does not remain in one place but in consequence of the destruction of the catalyst, it moves in the direction of the flow of the reactants. The result is that the destruction of the catalyst is not limited to a small zone or amount but progresses throughout the entire body of catalyst. Serious losses of catalyst, re-

ductions in yields, production of impurities, and v other disadvantages result from such an uncontrolled mode of operation.

In the past, control of the temperature in exothermic catalytic conversion processes has been effected usually by means of a fluid medium in indirect heat-exchange relationship with the catalyst. To be successful, this mode of operation requires that the heat exchange be highly eflicient. The reaction, therefore, is carried out generally in a plurality of relatively small and/or narrow catalyst chambers arranged in indirect heat-exchange relationship with the temperature-controlling medium. Such catalyst-chambers are made usually of tubes having a diameter of the order of 0.25 to 1.5 inches or of concentric tubes that form annular zones having thicknesses of the same order of magnitudes. Heat is removed by the temperature-controlling medium, which is in contact with the walls of the catalyst chambers. Equivalent systems in which temperature-controlling means are placed in. contact with the catalyst, such as tubular members positioned within the catalyst body and containing a liquid of suitable boiling point or some other temperature-controlling medium, have also been proposed and used with some measure of satisfaction.

Such previously proposed catalytic conversion systems have a number of outstanding disadvantages, among which may be mentioned: the high cost of manufacture of the many catalystchambers required; the high cost of certain heatexchange media such as mercury, diphenyl, and the like; the difliculty of making and maintaining fluid-tight connections or joints; the comparative inconvenience of catalyst replacement;

. and the difficulty of preventing leakage of the temperature-controlling medium, which may be toxic as well as expensive. In spite of these disadvantages, such systems have been used because many catalytic conversions must be effected within a narrow temperature range. If an efficient heat-exchange relationship is not maintained, the catalyst may become too hot; this may result in the production of impurities in the product by destructive hydrogenation and/or other undesired reactions and in the destruction of the activity of the catalyst. The necessity of an efficient heat-exchange relationship between the catalyst and the temperature-controlling medium precludes the use of comparatively large bodies of catalyst in an individual catalyst improved process of effecting the catalytic non destructive hydrogenation of unsaturated hydrocarbons boiling in the motor fuel range.

Another object of this invention is to provide an improved process for the catalytic non-destructive hydrogenation of the polymers of normally gaseous olefin hydrocarbons.

It is a further object of this invention to provide an improved process of eflecting hydrogenation of gasoline-boiling-range olefin hydrocarbons without use of a multiplicity of relatively small tubular ornarrow annular (or equivalent) catalyst-chambers in indirect heat-exchange relationship with a temperature-controlling medium.

Still another object of this invention is to provide an improved process for the catalytic nondestructive hydrogenation of organic compounds wherein the un-hydrogenated reactants absorb exothermic heat of reaction by direct heat exchange. i

A further object of this invention is to provide a two-stage process for the non-destructive, catalytic hydrogenation of unsaturated hydrocarbons.

Other objects and advantages of the invention will be apparent to those skilled in the art from the following description, the accompanying drawing, and the appended claims.

I have now found that catalytic, non-destructive hydrogenation of unsaturated organic compounds or materials may be effected in an emcacious, economical, and advantageous manner when the operating conditions are so selected that only a small fraction or portion of the total hydrogenation can take place in any one portion or zone of a catalyst bed. I have also found that this may be accomplished by conducting the hydrogenation in a plurality of catalyst zones or chambers, having all the while an excess of hydrogen present over that required to hydrogenate the unsaturated material present, and preferably also having an appreciable proportion of saturated material present. By catalytic nondestructive hydrogenation I mean, broadly, the addition of hydrogen to an unsaturated bond between two adjacent carbon atoms without separation of the carbon atoms, such as occurs during the saturation of olefin hydrocarbons with hydrogen to form parafiln hydrocarbons having the same number of carbon atoms per molecule, and generally having also the same carbon skeleton, the formation of tristearin from triolein by the catalytic addition of hydrogen, and the like. More particularly my invention deals with the formation of saturated hydrocarbons in the motor fuel boiling range, such as the formation of parafiins from olefins, of cyclohexane from cyclohexene, or benzene or the like, and of other naphthenes from aromatics or hydroaromatics. Such catalytic non-destructive hydrogenations are not equivalents of each other, but the reactions which occur are quite similar, they are promoted by similar catalysts, and for a given process the most desirable conditions of operation in any particular case may be readily determined by trial.

In one modification of my invention a relatively small amount of unsaturated material in admixture with hydrogen is introduced into a hydrogenation chamber which contains a su table body of solid hydrogenation catalyst, and the greatest dimension of which is in the direction of flow of fiuids through it. Preferably there is associated with this unsaturated material a substantial amount of saturated material. which may well be a portion of the efluent of the hydrogenation chamber. I have found that at least one mol of such saturated material should be present for every mol of unsaturated material introduced to the process, and preferably the amount of saturated material should be 'higher' than this although, except in the latter stages of the process, the saturated material need not be more than about mol per cent of the total of the saturated and unsaturated material. A preferred ratio of saturated to unsaturated material will generally be found between about 2:1 and 5:1.

In this modification of my process, after this initial amount or portion of unsaturated material has been substantially saturated with hydrogen, an additional amount or portion of unsaturated material is added to the mixture. This portion immediately becomes diluted with saturated material, some of which has been formed in the first part of the hydrogenation chamber. As reaction progresses additional amounts or portions of material to be hydrogenated are added up to the capacity of the hydrogenating chamber and the catalyst therein to produce substantially completely saturated hydrocarbons. One of the important advantages of such a procedure is the close control of reaction temperature that is afforded. Thus, as the hydrogenation proceeds, th temperature of the mixture tends to rise, due to the exothermic nature of the reactions which occur. I have found that this temperature rise can be quite adequately controlled by introducing these subsequent portions of unsaturated material at temperatures appreciably below the reaction temperature, whereby the resultant mixture has a lower temperature, but one which will still be within a reaction range.

With a fresh, active catalyst, the initial temperature can be in the range of 200 to 300 E, the additional streams of hydrocarbon being added at temperatures between about 50 to F. As the process continues and the catalyst loses activity, the inlet temperature may be raised, whereby the extent of hydrogenation remains substantially constant and the throughput of the process can be kept constant. The amount and extent of such a temperature change may be guided and controlled in connection with the composition of the eilluent of the process and the amount of unsaturated material which has not been saturated. However, care should be taken to control the temperature so that the highest temperature in the catalyst chamber is not above a decomposition temperature, and generally the maximum temperature should be kept below about 650 to 700 F., and preferably below 600' F. As the temperature is raised in this manner, the temperatures of the streams which are added along the catalyst chamber may be a little higher than those herelnbefore indicated.

The points at which the portions of unsaturated material are added may be spaced equally along a uniform reaction chamber, or they may be spaced at distances which increase in the di rection of flow through the chamber. As the mixture proceeds through the chamber and more material is added, the flow rate becomes higher and the reaction time becomes shorter, and more contact with the catalyst is needed to insure sufif necessary or desired additional hydrogen may be added at one or more of these points of addition. After the addition of the last portion of unsaturated material, a sufiicient extent of the hydrogenation catalyst should be provided so that the eilluent of the chamber will be essentially. saturated, or at least so that saturation will have progressed to the desired extent. Instead of adding unsaturated material at various points in a hydrogenation catalyst, a substantially equivalent method, insofar, as the results are concerned, is to use a series of smaller chambers,

adding unsaturated material at the inlet to each I chamber.

In another modification of my process, a mixture of unreacted unsaturated material and of partially reacted material containing both saturated and unsaturated material is passed through one hydrogenation chamber containing a body of hydrogenation catalyst and wherein the saturation is not allowed to go to completion, a portion of the eiiluent is recycled to the inlet of the chamber, and the rest of the eifluent material is passed to a second hydrogenation chamber which contains a body of a suitable solid hydrogenation catalyst and which is maintained undersubstantially adiabatic conditions. This second chamber is rather thoroughly insulated, so that there is little if any loss or gain of heat through its walls during hydrogenation. In such a mode of operation the material introduced into it is approximately 90 per cent or more saturated, and it is only the last remaining small amount of unsaturated material which undergoes reaction. Under such conditions the temperature rise through the chamber, provided the efiluent material from this second chamber is at least about 99 per cent or more saturated, will be an amount up to about '15 to. 100 F., when all the material is in the vapor phase, but will only be about R, if an appreciable amount of the hydrocarbon material is in the liquid phase and vaporizes as the temperature tends to rise, so that if the material charged to this chamber is about 90 per cent saturated its temperature should not be above about 550 to 600 F. at the most, and should generally be appreciably less. I have often found it advisable or advantageous to use a fresh, highly active batch of catalyst in this adiabatic chamber. Such a catalyst remains highly active for an extended period of time, and tends to promote complete saturation at a somewhat lower temperature. In case the eiliuent of the first hydrogenation chamber is at an elevated temperature in the region of 600 F. or higher. it may be desirable at times to cool it s mewhat before introducing it into the adiabatic chamber.

I have further found that a very desirable mode of operation is obtained by combining these two modifications. and operating them together as a further modification. Thus, in connection with the first hydrogenation chamber, multipoint addition of unsaturated material may be employed. but the extent of reaction after the last addition of unsaturated material has been made is limited, so that the total eilluent from this chamber does not contain much more than about 90 mol per cent of saturated material. All or a part of the effluent is then passed directly to an adiabatic chamber wherein essentially complete saturation takes place. One desirable method of operation is to recycle a part of the eiiluent of the first chamber to be mixed with the initial portion of unsaturated feed stock, and to send only the remainin portion of the eflluent to the adiabatic chamber. Partial or complete separation of recycled material from hydrogen may or may not take place as is found desirable. Hydrogen not separated is recycled as well as the other material, and it is generally desirable to operate in a manner such that a more or less representative portion of the eiliuent of the first chamber is recycled.

My invention will now be described with reference .to the accompanying drawing, which shows a diagrammatic view of a preferred arrangement of apparatus. It will be obvious to those skilled in the art that modifications other than the specific arrangement shown may be used without passing beyond the scope of the invention.

An unsaturated feed stock is compressed to a suitable pressure by a pump not showmand enters the system through pipe I into a purifier 2, wherein it may be freed from undesirable c-rtroublesome impurities, such as those that may have a deleterious effect on the catalyst to be used for effecting hydrogenation. For example, if the feed stock contains sulfur compounds to an extent greater than that tolerated readily by the catalyst, purifier 2 may contain a material capable of decreasing the sulfur content to a value below the maximum tolerated by the catalyst. Such a material may be a body of the hydrogenation catalyst, after it had been used for effecting hydrogenation, for a catalyst that is too far spent to effect further hydrogenation economically may be still highly active for the adsorption of sulfur, or it may aid otherwise in removing impurities from such a charge stock.

From the purifier 2 the feed stock flows into distributor-pipe or manifold 3, from which it is distributed at will through a multiplicity of branches, such as pipes 4, 5, 6, 1, and 8, provided with control valves 9, III, ll, [2, and i3 and with fiowmeters l4, l5, l6, l1, and I8, into the heat exchangers I9, 20, 2|, 22, and 23.

Simultaneously, hydrogen is compressed to a suitable pressure by a pump not shown and enters the system through pipe 24 passing into a purifier 25, wherein it may be freed from undesirable or troublesome impurities. From the purifier 25 it flows into the distributor-pipe or manifold 26, from which it may be distributed at will through a multiplicity of branches. such as pipes 21, 23, 29, 30, 3!, and 35 provided with control valves 32, 33. 34, 35, 36, and 86 and with fiowmeters 31, 33, 33, 40, 4|, and 81 into the pipes 4, 5, 6, 1, and 8 and thence into the heat exchangers I9, 20, 2|, 22, 23, and 88. Generally all or a large part of th hydrogen will be introduced to, the inlet of the system through pipes I such that essentially only one phase is present,

may be in a position other than vertical, if so desired. A suitable hydrogenation catalyst may be any material that promotes the addition of hydrogen to unsaturated carbon to carbon linkages, such as nickel, copper, iron, palladium, platinum, cobalt, chromium, manganese, titanium, molybdenum, vanadium and the like, in a finely divided state or in the form oi oxides. and either alone or, as is preferable, in combination with one or more promoters, preferably supported on a porous material 'such as porcelain, kieselguhr, pumice. bauxite. etc.

Ii, in the catalytic hydrogenation chamber 41, the unsaturated hydrocarbons are hydrogenated to an extent short of total saturation, the eiiiucnt of this hydrogenation chamber 41, containing saturated hydrocarbons, any unreacted unsaturated hydrocarbons, and the excess hydrogen passes through pipe 44 and at least a portion of the stream passes into a second hydrogenation chamber 49, which is iilled with a suitable hydro.. genation catalyst such as one of those already mentioned and which may or may not be the same catalyst as is used in the chamber 41. This second hydrogenation chamber 49 is preferably rather thoroughly insulated, so that very little heat passes through the walls of the chamber tending either to cool the chamber or to heat it while in use. In this manner it is maintained under substantially adiabatic conditions, except as an entering or eiiiuent stream may add or extract sensible heat. It desired, such insulation may contain heating and/or cooling coils, which will aid in heating the chamber and catalyst at the start 01' a run or to cool the same at the end of a run. However, if such means are present, I do not intend that they shall be used to any extent during the actual use of the chamber, so that the adiabatic characteristics of this chamber will be preserved. In this second hydrogenation chamber, or adiabatic hydrogenator, 49 any unsaturated hydrocarbons which have passed from chamber 41 without reaction therein are hydrogenated substantially completely into saturated hydrocarbons. In general, the unsaturate content of the hydrocarbons entering the adiabatic chamber 49 is less than ll per cent and the prevailing conditions are such that the temperature rise caused by hydrogenation to substantially 100 per cent saturation does not exceed the temperature range in which the catalyst can effect hydrogenation without unduly great deactivation or deterioration of the catalyst or decomposition of hydrocarbons. The volume 01' catalyst in the adiabatic hydrogenation chamber 49 per unit quantity unsaturate treated may be two or more times that used in chamber 41, as its purpose is to effect complete hydrogenation. It desired, a partial cooling of the eiiiuent from chamber 41 which is sent to adiabatic chamber 49 may be effected by means not shown.

The adiabatic hydrogenation chamber 49 may be by-passed, as through valve 42 and pipe 83, if complete hydrogenation is not desired, or it a sufficiently high degree of saturation is eflected in hydrogenation chamber 41. If desired additional hydrogen may be added by opening valve 86 in pipe 85 and passing any desired amount of hydrogen from manifold 28 through meter 81, heat exchanger 88, and pipe I! to pipe 48 immediately prior to the inlet of the adiabatic hydrogenation chamber 49.

The saturated hydrocarbons and excess hydrogen pass from the hydrogenation chamber 49 through valved pipe 50 into separator 5|, wherein they are separated into the saturated product, which leaves the separator by valved pipe 52, and

pump 54 into pipe 24, to be used again in the process.

Part of the eiiiuent material may be withdrawn from pipe 48 by means of pipe II, which is provided with control valve Ii, whether the adiabatic hydrogenation chamber 40 is used or not. This material is pumped by pump 51 through pipe II and through branch-pipe II, which is provided with a control-valve 80 and a flowmeter ll, into pipe 4, or through branch-pipe 42, which is provided with a control valve 83 and a ilowmeter l4, into pipe 42. Similarly, if adiabatic hydrogenation chamber 49 is used, part oi the mixture 0! hydrogen and substantially completely hydrogenated material may be withdrawn from pipe II by means of pipe 65 which is provided with a control-valve 66, and pumped into pipe 4 or pipe 42. In either case, such a recycled stream is practically completely saturated as compared with the hydrocarbon stream charged to the process, and serves as an adequate diluent.

The function of the heat exchangers ll, 2|, II, 22, and 23 is to adjust the temperature oi the material passing therethrough so that the material may pass thence into the hydrogenation chamber 41 and contribute to the maintenance of the desired temperature and extent oi. hydrogenation. The heat exchangers may pre-heat the mixture of unsaturated feed stock and hydrogen, or they may cool the mixture of unsaturated feed stock and hydrogen, in accordance with the requirements indicated by the temperature and/or the extent of hydrogenation prevailing in the corresponding zone in the chamber 41. If these heat exchangers are used to preheat the material passing through them, it will generally be only to a limited extent, so that the mixture from any one exchanger except the first will enter the hydrogenation chamber 41 at a temperature somewhat below the temperature of the mixture in the hydrogenation chamber immediately preceding the point of addition. If desired, further physical treatment may be given to the mixtures entering chamber 41, by apparatus not shown. For instance, such physical treatment may include a thorough mixing or physical emuisification of the organic material with hydrogen which into hydrogen which passes through pipe 53 and may be added at any point. The temperature in the chamber 41 may be determined by any suitable means, such as the thermometers 41, ll,

' 6!, and 10.

The pipes 42, 43, 44, 45, and 46 may enter the hydrogenation chamber 41 according to any desired arrangement. They may be spaced at increasing distances in the direction of flow oi the material as indicated in the drawing, or they may be spaced equally throughout the length 0! the hydrogenation chamber 41. Under an arrangement such as that indicated the flow of unsaturated material in each of the several pipes 42, 43, 44, 45, and 46 may be made substantially the same and yet notwithstanding the increasingly greater dilution of the unsaturated material by already hydrogenated material in the direction of flow. substantially equal times of contact oi-the unsaturated material with the catalyst in every zone in the hydrogenator 41 may be obtained.

The proportions of hydrogen and unsaturated material passing through the heat exchangers I9, 20, 2|, 22, and 23 may be controlled in any manner desired by means of the control valves 9 to I3 and 32 to 38. For example, in a possible mode of operation, hydrogen may be passed only through exchanger I9 and not through the other stock passing through heat-exchanger I! would be heated sumciently for the reaction to take place in chamber 41; and cold feed stock would be introduced as such through pipes 43, 44, 45, and 45, or it would first be heated in exchangers 20, 2|, 22, and 23 only to such a degree that the heat developed by its subsequent hydrogenation would be consumed as sensible heat.

The conditions maintained in the chamber 41 depend somewhat on the catalyst and suitable conditions may be found readily by trial. In general, the temperature will be in the range 200 to 700 F. and the pressure will be in the range 20 to 2000 pounds per square inch. A preferred temperature range is 400 to 500 F. and a preferred pressure range is 500 to 1500 pounds per square inch.

If the unsaturated feed stock does not contain impurities in troublesome amount, the purifier 2 is not needed and may be bypassed by closing valve II in pipe I and opening valve I2 in pipe 13. Similarly, if the hydrogen entering the process through pipe 24 does not require purification, purifier 25 may be by-passed by closing valve 14 in pipe 24 and opening valve 15 in pipe 16; likewise, if the hydrogen in pipe 53 does not require purification, purifier 25 may be by-passed by closing valve TI in pipe 53 and opening valve I8 in pipe 19.

If desired, part or all of the hydrogen in pipe 53 may be removed from the system through valve 80 and pipe 8|.

The ratio of recycled hydrocarbon material in pipe 58 to fresh unsaturated feed stock in pipe 42 may be between about 1:1 to about :1, and is preferably between 2:1 and 5:1.

The hydrocarbons in the hydrogenation chamber 41 and in the adiabatic hydrogenation chamber 43 may be present in the liquid phase, in the vapor phase, or in both liquid and vapor phases. It is preferred to introduce the hydrocarbons in the liquid phase, as thereby the heat evolved by the hydrogenation may be used up as latent heat in the vaporization of part or all of the hydrocarbons; thus the temperature of the catalyst is prevented in-some measure from becoming too high. For example, in a run made with diisobutylene diluted with twice its amount of the isooctane made by its hydrogenation, at 2 pressure of 750 pounds per square inch and a hydrogen concentration of mol per cent, the temperature at the inlet to the hydrogenation chamber, which was filled with a nickel-copperalumina catalyst supported on pumice, was 400 F.; at this temperature two-thirds of the hydrocarbon material was liquid. The temperature increases by 150 F. during the hydrogenation of the diisobutylene. On the other hand, when the temperature of the catalyst is 500 F., at which temperature virtually no hydrocarbons are in the liquid state, the temperature increase caused by the hydrogenation is 250 F.

The portions of the pipes 42 to 46 that are within the catalytic hydrogenation chamber 41 may be perforated to provide even distribution of the incoming material. Each of these portions may be modified by being constructed to form a perforated tube in the shape of a loop, spider, or circle, or the like. If desired, the zones of catalytic hydrogenation chamber 41 into which these portions extend may be kept devoid of catalyst, as for example by the use of perforated partitions, and may have a restricted crosssection.

Emample I As an example of the operation of my process, a hydrocarbon fraction in the motor fuel boiling range, and comprising essentially hydrocarbons produced by the catalytic polymerization of olefins produced by the thermal dehydrogenation of isobutane, was saturated with hydrogen in the presence of a nickel-copper-alumina catalyst. The catalyst was prepared by forming a concentrated aqueous solution containing nickel nitrate, copper nitrate, and aluminum nitrate, mixing with this solution crushed pumice of 6 to 8 mesh in size, boiling the resultant slurry, and finally drying and calcining the pumice so treated. This produced an intimate mixture of the oxides of nickel, copper, and aluminum on the pumice which, after treatment in the presence of hydrogen, resulted in an intimate mixture of nickel, copper, and alumina on the pumice. This catalyst is known as a nickel-copper-alumina catalyst.

The nickel-copper-alumina catalyst is placed in a vertical catalyst chamber. A stream of hydrocarbons consisting of the olefin polymers above mentioned is divided into three portions of about the same volumes. The first portion is mixed with about two volumes of saturated hydrocarbons produced in the process. This mixture is charged to the top of the catalyst chamber along with sufficient hydrogen to react with all the unsaturated hydrocarbons charged to the process with sufficient excess so that the efiluent of the chamber comprises 50 mol per cent of free hydrogen. The reactants in the catalyst chamber are maintained under a total pressure of about 650 pounds per square inch, and the mixture is initially charged to the top at a temperature of about 320 F. As reaction proceeds hydrogen is consumed and heat is evolved, and about M; of th way down the bed from the top the temperature is about 445 F. At this point a second portion of the olefin polymer charge stock is added to the mixture at a temperature of about 100 F. In this manner the olefin content of the reaction mixiure is increased and the temperature lowered to about 410 F. but is still high enough for efilcient hydrogenation. Just past the middle of the bed of catalyst the temperature of the reactants is about525 F. and the third and final portion of the olefin polymer charge stock is The eflluent oi the chamber is cooled to about F. and passed to a separator, where a separation is made between .ases which comprise essentially free hydrogen, a: i a saturated hydrocarbon liquid. The gas is mixed with fresh hydrogen and returned to the inet of the chamber. A portion of the hydrocarbon liquid, consisting of two- 'fifths of this liquid, is returned to the inlet of the chamber as recycle stock, and the remaining three-fifths is recovered as finished product. As the catalyst becomes deactivated, th temperature is gradually allowed to rise, thus keeping the extent of hydrogenation the same for a constant volume of charge stock.

Example II The following is given as an exampl of the operation of another modification of my process. A nickel-copper-alumina catalyst is charged to each of two vertical catalyst chambers, the second of which contains about one-half the amount of catalyst which is in the first chamber. This second chamber is thoroughly insulated, so that with the interior at reaction temperature, such as 400 to 600 F., there is a minimum of heat loss through the walls of this chamber, that is to say, it operates under essentially adiabatic conditions. A stream of hydrocarbons consisting essentially of olefin polymers is mixed with a portion of the hydrocarbon eilluent of the first chamber in such amounts that the molecular ratio of satiu'ated to unsaturate hydrocarbons is about 2:1. This composite stream is passed to the inlet oi the first catalyst chamber under a pressure of 775 pounds per square inch and at a temperature of about 355 F., along with hydrogen in an amount about four times that required to react with the unsaturated hydrocarbons present. The flow through this first chamber is such that saturation of the unsaturated hydrocarbons does not proceed to completion, and about 8 per cent of the hydrocarbon eflluent of this chamber is still unsaturated. A portion amounting to slightly more than two-thirds of this eiliuent is separated and returned to the inlet of this first chamber to be mixed with fresh unsaturated hydrocarbons as described. The remaining portion of the eiiiuent, which contains a large excess of free hydrogen, is

cooled somewhat and passed to the second, or

adiabatic chamber without any substantial reduction in pressure and at a temperature of about 400 F. In this second chamber, hydrogenation of unsaturated hydrocarbons proceeds essentially to completion, and the hydrocarbon eifluent contains less than 0.2 per cent of unsaturated hydrocarbons. There is a temperature rise of about 10 F. through this adiabatic chamber, while the temperature rise through the first chamber is about 125 R, an appreciable loss of heat to the atmosphere taking place.

By the practice of this invention gasolinerange hydrocarbons prepared by catalytic and/or thermal polymerization of gaseous olefins may be hydrogenated catalytically and non-destructively to saturated hydrocarbons suitable for use in motor fuel either directly or after being blended with other motor fuel constituents such as straight run gasoline, saturated gasoline produced by alkylation, and the like. The hydrogenation is effected in an efiicacious, economical and advantageous manner, the temperature of large bodies of catalyst being controlled below the sintering temperature of the catalyst by the controlled portionwise addition of suitably conditioned reactants.

I do not wish to exclude from my invention certain modifications or variations that will be obviwe to those skilled in the art. For example, the eiiiuents of the hydrogenation chambers may be placed in heat exchange relationship with the ingoing stream of reactants at various places throughout the process and to any desired degree. Hence, it is to be understood that, within the scope of the appended claims, the invention is as extensive in scope and equivalents as the prior art allows.

I claim:

1-. An improved process for the catalytic, nondestructive hydrogenation of unsaturated organic material which comprises passing a charge stock comprising substantially unsaturated organic material to which has been added at least an equal volume of saturated organic material and a suitable amount of hydrogen to a first hydrogenation chamber containing a hydrogenation catalyst while at a superatmospheric pressure and at a non-destructive hydrogenation temperature, adding additional portions of said unsaturated organic material at a plurality of points to the mixture in said hydrogenation chamber and maintaining a reaction time such that only about 90 mol per cent of the organic material in the emuent of said chamber is saturated, passing at least a portion of the emuent of said first hydrogenation chamber through a second hydrogenation chamber containing a hydrogenation catalyst and maintained under substantially adiabatic conditions within a temperature range suitable for non-destructive hydrogenation, and separating from the eilluent of said second chamber a fraction comprised essentially of saturated material produced.

2. An improved process for the catalytic, nondestructive hydrogenation of unsaturated organic material, which comprises passing a mixture, containing liquid organic material not more than 50 per cent of which is unsaturated and a suitable quantity of hydrogen, under a superatmospheric pressure through a body of hydrogenation catalyst maintained at a temperature suitable for the nondestructive hydrogenation of said unsaturated Organic material and such that a substantial amount of said organic material exists in the vapor phase, adding additional portions of unsaturated organic material at a plurality of points to the mixture in contact with said body of hydrogenation catalyst, each said additional portion of unsaturated organic material being added at a temperature lower than the adjacent reaction temperature and substantially in liquid phase, and separating a fraction comprised essentially of saturated organic material from the eiiiuent of said body of hydrogenation catalyst.

3. An improved process for the non-destructive hydrogenation of unsaturated hydrocarbons, which comprises passing a portion oi a charge stock comprised substantially of liquid unsaturated hydrocarbons, in admixture with at least an equal volume of liquid saturated hydrocarbons and with a suitable amount of hydrogen, under a superatmospheric pressure and at a hydrogenation temperature such that a substantial amount of said organic material exists in the vapor phase and between about 200 and 600 F. through a hydrogenation chamber containing a suitable hydrogenation catalyst wherein non-destructive hydrogenation of unsaturated hydrocarbons takes place and heat is evolved, adding additional portions of said charge stock at a plurality of points to the hydrogenation chamber under a superatmospheric pressure and at a temperature below the temperature existing in said hydrogenation chamber and such that said added hydrocarbons are substantially in liquid phase, separating from the eflluent of said hydrogenation chamber a representative portion thereof containing saturated hydrocarbons and returning said portion to be mixed with the first portion 01' said charge stock, and recovering a hy rocarbon mixture containing essentially hydrogenated hydrocarbons from the remaining portion of said eiiluent.

4. An improved process for the catalytic, nondestructive hydrogenation of unsaturated hydrocarbons in the motor fuel boiling range, which comprises passing a portion of a charge stock comprised essentially of unsaturated hydrocarbons in the motor fuel boiling range, in admixture with at least about an equal volume of saturated hydrocarbons of a similar boiling range and with hydrogen in excess of that sufficient to hydrogenate all of said charge stock, saidmixture being under a superatmospheric pressure and at a temperaturebetween about 200 and 600 E, into the top of an elongated, vertical hydrogenation chamber containing a body of solid hydrogenation catalyst, maintaining in said chamber hydrogenating conditions such that a substantial amount of said organic material exists in the vapor phase, adding additional portions of said charge stock under a superatmospheric pressure at a plurality ofpoints to the mixture in said hydrogenation chamber, each of said additional portions being added substantially in liquid phase and in an amount such that the resultant mixture contains a ratio of saturated to unsaturated hydrocarbons between 1:1 and :1 and at a temperature which is substantially below the temperature existing in said chamber immediately prior to the point of addition and such that the final temperature of the mixture is at a non-destructive hydrogenating temperature below 700 F., and separating from the eflluent of said chamber a fraction containing. saturated hydrocarbons in the motor fuel boiling range.

5. An improved multistage process for the nondestructive hydrogenation of unsaturated hydrocarbons, which comprises passing a first portion of a charge stock comprised substantially of unsaturated hydrocarbons to a first hydrogenation chamber containing a hydrogenation catalyst, said first portion of charge stock being in admixture with a portion of the eiiluent of said first hydrogenation chamber and containing saturated hydrocarbons in an amount at least equal to the total amount of unsaturated hydrocarbons in the final mixture, and also in admixture a suitable amount of hydrogen, the said mixture being at a suitable superatmospheric pressure and at a nondestructive hydrogenation temperature, adding additional portions of said charge stock at a plurality of points to the mixture in said hydrogenation chamber and maintaining a reaction time in said chamber such that at least 90 mol per cent of the hydrocarbons in the eiiluent of said chamber are saturated, separating from the eiiiuent of said hydrogenation chamber a portion thereof and passing said portion to be mixed with fresh charge stock, passing a remaining portion of the eiiiuent of said first hydrogenation chamber, still under a superatmospheric pressure and at a nondestructive hydrogenation temperature to a second hydrogenation chamber containing a hydrogenation catalyst and maintained under substantially adiabatic conditions wherein unsaturated hydrocarbons are substantially completely hydrogenated, and removing from the eflluent of said second chamber a fraction containing saturated hydrocarbons so produced.

6. The process of catalytic non-destructive hydrogenation of unsaturated hydrocarbons, comprising diluting unsaturated hydrocarbons with recycled hydrogenated material in a ratio between 1 to 1 and 1 to 10, adding hydrogen in exa body of hydrogenation catalyst at a temperature of 200 to.'i00 1'5, adding additional portions of unsaturated hydrocarbons at a plurality of points in the body of catalyst, effecting nondestructive hydrogenation short of complete saturation of the unsaturated hydrocarbons in said body 'of catalyst, and completing the nondestructive hydrogenation with a second body of hydrogenation catalyst under substantially adiabetic conditions.

7. In a multistage, catalytic process for the non-destructive hydrogenation of unsaturated organic compounds, the steps which comprise passing unsaturated organic material to be hydrogenated, in admixture with at least an e'qual volume of organic material which has been hydrogenated to an extent of at least 90 per cent and hydrogen in excess of the amount necessary for hydrogenation of all the material to be ydrogenated, under a superatmospheric pressure over a hydrogenation catalyst maintained at a reaction temperature less than about 700 F. in a hydrogenation chamber, maintaining a reaction time such that at least 90 per cent of the desired non-destructive hydrogenation takes place, separating from the emuent of said chamber a substantial portion thereof and returning it to the inlet of said chamber, passing at least a portion of the remainded of said eiiiuent, still under a superatmospheric pressure and at a reaction temperature less than 700 F. through a second hydrogenation chamber containing a hydrogenation catalyst under substantially adiabatic conditions and wherein non-destructive hydrogenation of unreacted material proceeds substantially to completion, and separating from the emuent of said second hydrogenation chamber organic hydrogenated material so produced.

8. An improved process for; the non-destructive hydrogenation of unsaturated hydrocarbons, which comprises passing into a hydrogenation chamber, containing a hydrogenation catalyst at a non-destructive hydrogenation temperature, a hydrocarbon mixture containing a high concentration of unsaturated hydrocarbons, in admixture with a mixture comprising a portion of the eiiiuent of said chamber containing therein hydrocarbons of which not more than 10 niol per cent are unsaturated hydrocarbons and in amount such that at least mol per cent of the total hydrocarbons are saturated hydrocarbons and with hydrogen in an amount in excess of that required to react with all the unsaturated hydrocarbons present, maintaining a superatmospheric pressure on the mixture in said hydrogenation chamber and a reaction time such that complete saturation of unsaturated hydrocarbons does not take place and such that the uncess, passing the mixture thus formed through saturated hydrocarbons in the eiiluent of said chamber are not more than 10 mol per cent of the hydrocarbons in said eiiiuent, separating from the eiiiuent of said chamber a portion thereof and passing said portion to the inlet of said chamber, passing a further portion of said eiiiuent, still under a superatmospheric pressure and at a non-destructive hydrogenating temperature to a second hydrogenation chamber containing a hydrogenation catalyst and maintained under hydrogenation of unsaturated hydrocarbons in the motor fuel boiling range, which comprises passing a charge stock comprised substantially completely of olefin hydrocarbons in the motor fuel boiling range to a first hydrogenation chamber containing a solid nickel-containing hydrogenation catalyst, said charge stock being in admixture with a portion of the eiiluent of said first hydrogenation chamber, in an amount such that the molar ratio of saturated hydrocarbons to olefin hydrocarbons in the final mixture is between 1:1 and 5:1, and also in admixture with hydrogen substantially in excess of that required to saturate all the olefin hydrocarbon, in said mixture, said mixture being under a superatmospheric pressure and at a reaction temperature between 200 and 700 F., maintaining a reaction time such that the olefin hydrocarbons in the eilluent of said chamber are not more than moi per cent of the hydrocarbons in said eiiluent, separating a portion of the eii'iuent of said first hydrogenation chamber and returning said portion to be mixed with hydrocarbons charged to the process, passing the remainder of said efiluent while still under a superatmospheric pressure and at a temperature between 200 and 600 F. into a second reaction chamber containing a solid nickel-containing hydrogenation catalyst and maintained under substantially adiabatic conditions wherein substantially complete hydrogenation takes place, and separating from the eilluent of said second hydrogenation chamber a fraction containing substantially saturated hydrocarbons in motor fuel boiling range so produced.

10. The process of claim 9 wherein the catalyst is a nickel-copper-alumina catalyst.

11. An improved process for the catalytic nondestructive hydrogenation of olefin polymers, which comprises passing a portion of a charge stock comprised essentially of olefin polymers, in admixture with at least about an equal volume of saturated hydrocarbons and with an excess of hydrogen, to the top of a vertical catalyst chamber which contains a solid hydrogenation catalyst and wherein conditions of temperature and pressure are maintained suitable for the non-destructive hydrogenation of said olefin polymers, adding additional olefin polymers at a plurality of points to the mixture in the catalyst chamber as said mixture passes down through said chamber, maintaining an excess of hydrogen in said chamber, passing at least a portion of the eilluent from the bottom of said vertical chamber through a second catalyst chamber which contains a suitable hydrogenation catalyst and which is maintained under substantially adiabatic conditions within a temperature range suitable for non-destructive hydrogenation, and recovering saturated organic material so produced from the eilluent of said adiabatic chamber.

12. An improved process for the catalytic nondestructive hydrogenation of unsaturated organic material, which comprises passing a mixture, containing vaporizable organic material not more than 50 per cent of which is unsaturated, and a suitable quantity of hydrogen to effect complete saturation of said material, under a super-atmospheric pressure through a body of hydrogenation catalyst maintained in an elongated catalyst chamber at a temperature suitable for the non-destructive hydrogenation of said unsaturated organic material and such that a substantial amount of said organic material exists in the vapor phase, adding at a plurality of points spaced increasingly further apart in the direction of fiow of the reactant material through said catalyst chamber additional portions of unsaturated organic material to the mixture in contact with said body of hydrogenation catalyst, each said additional portion of unsaturated organic material being added at a temperature lower than the adjacent reaction temperature and substantially in liquid phase, and separating a fraction comprised essentially of saturated organic material from at least a portion of the emuent of said body of hydrogenation catalyst.

13. An improved process for the catalytic, nondestructive hydrogenation of unsaturated organic material, which comprises passing a charge stock comprising substantially unsaturated organic material to which has been added at least an equal volume of saturated organic material and a suitable amount of hydrogen to a first hydrogenation chamber containing a hydrogenati0n catalyst while at a superatmospheric pressure and at a non-destructive hydrogenation temperature, adding at a plurality of points spaced increasingly farther apart in the direction of flow of reactant material additional portions of said unsaturated organic material to the mixture in said hydrogenation chamber and maintaining a reaction time such that only about mol per cent of the organic material in the eilluent of said chamber is saturated, separating from said effluent a portion thereof and passing said portion to be mixed with fresh charge stock, passing a remaining portion of the eiiluent of said first hydrogenation chamber, still under superatmospheric pressure and at a non-destructive hydrogenation temperature to a second hydrogenation chamber containing a hydrogenation catalyst and maintained under substantially adiabatic conditions wherein unsaturated organic material is substantially completely saturated, and removing from the eiiluent of said second chamber a fraction containing saturated material so produced.

14. An improved process for the catalytic nondestructive hydrogenation of liquid unsaturated organic material, which comprises passing a mixture comprising liquid saturated organic material and an initial portion of liquid unsaturated organic material in a ratio between about 1:1 and 5:1 and a suitable quantity of free hydrogen to the top of an elongated, vertical mass of solid hydrogenation catalyst maintained in a catalyst chamber at a temperature and under a superatmospheric pressure suitable for the non-destructive hydrogenation of said unsaturated organic material, said temperature and pressure being so correlated that a substantial amount of said organic material exists in the vapor phase, adding additional portions of said unsaturated organic material as a liquid at a plurality of points 15. An improved process for the catalytic nondestructive hydrogenation of unsaturated organic material, which comprises passing a mixture containing organic material of which not more than 50 per cent is unsaturated together with an excess of hydrogen under a superatmospheric pressure downwardly through a first hydrogenation chamber containing a body of hydrogenation catalyst maintained at a temperature suitable for the non-destructive hydrogenation of said unsaturated organic material and such that said organic material exists in both vapor and liquid phases, maintaining a time of reaction such that hydrogenation of unsaturated material is incomplete and also such that at least 90 mol per cent of the organic material in the eiliuent of said chamber is saturated, passing at least a representative portion of the efliuent of said first hydrogenation through a second hydrogenation chamber containing a body of hydrogenation catalyst which is maintained un der substantially adiabatic conditions and within a temperature range suitable for non-destructive hydrogenation and such that said organic material is present both in the liquid and vapor phase, and completing the hydrogenation of unsaturated organic material in said second hydrogenation chamber.

16. In a catalytic process for the non-destructive hydrogenation of organic compounds, the steps which comprise passin a portion of the organic material to be hydrogenated, in admixture with at least an equal volume of hydrogenated material and with a suitable amount of hydrogen, under a superatmospheric pressure and at a non-destructive hydrogenation temperature such that a substantial amount of said organic material exists in the vapor phase through a hydrogenation chamber containing a body of solid hydrogenation catalyst, adding further portions of said organic material to be hydrogenated at a plurality of points in said hydrogenation chamber under a superatmospheric pressure and at a temperature such that said added organic material is substantially in liquid phase and is at a temperature such that the final temperature of the material in said hydrogenation chamber adjacent to a point of introduction is within a desired non-destructive hydrogenation temperature range, withdrawing an efliuent stream from said hydrogenation chamber, returning a representative portion of said stream to the inlet of said chamber, and separating hydrogenated organic material from the remaining portion of said effluent.

FREDERICK E. FREY. 

